SAN DIEGO — In spring training, the Nationals said their job this season was to knock the Mets off the mountain top of the NL East.

They are more than halfway home with a six-game lead in the NL East while the Mets are struggling with injuries. At the All-Star break last season, the Nationals owned a two-game lead and collapsed in the second half as the Mets captured the division and the pennant.

Bryce Harper and the 54-36 Nationals have no intention of taking their foot off the gas this year.

“Our team as a whole, if we can just stick together and do what we can [the second half] I think we’ll be just fine,” Harper told The Post before Tuesday’s All-Star Game at Petco Park. “When you are down you want to get ahead, and when you are ahead you want to get more and more ahead, so that’s the mentality we have as a team.”

Asked specifically about the 47-41 Mets and their problems, including key injuries to Matt Harvey, David Wright and Lucas Duda, Harper said, “I think we’ll be fine and keep worrying about what we can control as a team. It’s really worrying about our team as a whole and that is the best we can do.”

The Nationals have come together as a team under Dusty Baker. The veteran manager in his first season in D.C. has taken the pressure off the Nats, who lead the Mets and Marlins by six games and have dominated the Mets in head-to-head play, winning nine of 13 games and outscoring them 63-36.

“When we do lose, we understand it’s part of the game as well,” Harper said.

There is no panic under Baker.

“It’s just how it is in there, we are a family in there, a group, a unit. I think we do a great job as a whole and if we can just stick together, win, loss or anything like that, then we will be just fine,” Harper said. “We got to just keep going, keep grinding, keep playing the game hard and keep playing the game right.”

Adding Daniel Murphy has been a huge addition for the Nationals — and subtraction for the Mets.

The Nationals’ Bryce Harper scores a run as Mets catcher Travis d’Arnaud looks on during a July game between to the two teams.Paul J. Bereswill

Murphy had the All-Star locker right next to Harper’s — this was the Nationals wing of the clubhouse with Stephen Strasburg next to Murphy and then Max Scherzer on the end. Tucked into the corner were the lockers of Jeurys Familia and Bartolo Colon. Noah Syndergaard was across the way in a temporary locker.

Murphy knows the progress the Nationals have made.

“Ninety games into the season we have put ourselves in a really good position, and we need to just continue to grind out at-bats, continue to get good pitching, give yourself a chance every day,” he said.

“It can be easy to look at 70 games as a whole,” he said of the second half, “but it’s more of just a focus on the next day and we have Pittsburgh coming in after the break, that’s all you can control, the next ballgame.”

Scherzer is confident the Nats can continue to succeed.

“You want to give yourself a pat on the back, but you also realize this is a 162-game season and we are only judged after 162, not 82. We know we have to continue to give this kind of effort for the rest of the season if we want to go where we want to be.

“Look, Marlins, Mets, I respect everybody in our division and everybody across the league and what they are trying to do. We have to continue to stay healthy and play at the level we are, get production from everybody,” Scherzer said.

“If we start to go in a tailspin, things can get sideways real quick on us,” he added. “That type of focus for the next two-and-a-half months is critical for our ballclub. We’ve won as a group. We’ve gotten production from all phases, we’ve played great team baseball.”

These Nats are going to keep pushing. The Mets have a much higher mountain to climb the second half this year.